Sometimes, to solve a problem you need to break it down into its basic elements. And the basic elements of the food shortage?

What comets are made of is the same thing you are made of, and what C-H-O-N spells is "food."
The Oort cloud was made up of millions of megaton-sized servings of chow. Back on Earth there were ten or twelve billion hungry people looking toward it and licking their lips.
There was still a lot of argument about what comets were doing there, out in the cloud. It was still arguable about whether they even came in families. Then Oort came along to try to make sense of it. His idea was that there was this great shell of comets all the hell around the solar system, and every once in a while the sun would reach out and pluck one out, and it would come loping in to perihelion. Then we would have Halley's comet, or the one that was supposed to have been the Star of Bethlehem, or whatever. Then a bunch of the guys began kicking that around, asking why exactly that should happen. It turned out it couldn't-not if you assume Maxwellian distribution for the Oort cloud. In fact, if you assume normal distribution, you also have to assume that there isn't any Oort cloud in the first place. You can't get the observed nearly parabolic orbits out of an Oort cloud; so said R. A. Lyttleton. But then somebody else said, well, who says the distribution can't be non-Maxwellian? And so it proved. It's all lumpy...

But it was there. It gleamed faintly blue in the darkness punctuated by stars, strangely shaped. It was the size of an office building and more oblong than anything else. But one end was rounded, and one side seemed to have a long, curved slice taken out of it.